1. Field of the Invention
The present invention relates generally to recyclable materials recovery systems, and more specifically, to a method and system for extracting useable hydrocarbon fuel products from waste material by conversion of fuel pre-products to gas.
2. Background of the Invention
A significant amount of waste material produced by residential and commercial facilities comprises plastics. Unless a recovery and/or recycling system is implemented, these plastics ultimately end up in landfills or are incinerated, producing undesirable gaseous pollutant products and ash. Some plastics may be recycled and used in part to form new plastic products, but it is possible to revert plastics to constituent chemical components or other compounds and re-use these compounds to produce fuel or for other manufacturing purposes.
Other waste materials, such as oilfield sludge (a mixture of tar, sand and dirt), absorbent materials that have been used to clean up oil spills and byproducts of other manufacturing and refining processes may contain useable hydrocarbon fuel components, also. It would be desirable to be able to process these materials in a similar manner as the method used to convert plastic waste material.
In particular, it is possible to produce a diesel-like fuel from hydrocarbon compounds that may be extracted from plastics and other waste. At high temperatures, the compounds are a gaseous mixture containing various hydrocarbons, aromatics and other gases. The gases may then be further separated and processed by distillation or other refining means to produce various usable fractions. In general, the resulting liquid condensed from the extracted gases cannot be burned in a diesel engine, as the spectrum of hydrocarbons produced from a mixture of plastics, or a solitary plastics contains a high fraction of “hot” components such as octane that will destroy a diesel engine unless the fraction is reduced to tolerable levels via a refining process. In general, all of the product should be useable, as octane can be used to make a gasoline fuel and lighter components may be “cracked” to form propane and synthetic natural gas fuels.
Several existing methods and systems have been proposed to revert plastic materials to gas from which fuel may be produced. In general, these systems fall into two categories: low temperature vapor extraction methods and high temperature pyrolytic conversion methods. The pyrolytic conversion methods require high energy input and generate gaseous fuel products such as butane and methane which require compression and large volume storage per BTU. The efficiency of conversion is very low, as the long-chain hydrocarbons present in plastics are converted to very short-chain hydrocarbon fuel components, wasting the energy available in the longer chains already present in plastics and other waste material.
Vapor extraction methods in the existing art have a low production throughput and are prone to a build-up of cross-linked polymers that must be removed from the equipment and a build-up of heavy hydrocarbon components that are not effectively removed from the system. They also are susceptible to environmental conditions such as barometric pressure and ambient temperature. These drawbacks have made existing vapor extraction systems not practical for both economic and production volume reasons.
Therefore, it is desirable to provide a method and system for extracting usable hydrocarbon fuel products from waste material in an energy efficient manner having high production throughput.